1 files changed, 98 insertions, 0 deletions
diff --git a/stm/audio.c b/stm/audio.c
new file mode 100644
index 0000000000..2df4e07941
--- /dev/null
+++ b/stm/audio.c
@@ -0,0 +1,98 @@
+#include <stdint.h>
+
+#include "stm32f4xx_rcc.h"
+#include "stm32f4xx_gpio.h"
+#include "stm32f4xx_dac.h"
+
+#include "nlr.h"
+#include "misc.h"
+//#include "lexer.h"
+//#include "lexerstm.h"
+#include "mpyconfig.h"
+#include "parse.h"
+#include "compile.h"
+#include "runtime.h"
+
+#define SAMPLE_BUF_SIZE (32)
+
+// sample_buf_in is always the same or ahead of sample_buf_out
+// when they are the same, there are no more samples left to process
+// in this scheme, there is always 1 unusable byte in the buffer, just before sample_buf_out
+int sample_buf_in;
+int sample_buf_out;
+byte sample_buf[SAMPLE_BUF_SIZE];
+
+bool audio_is_full(void) {
+    return ((sample_buf_in + 1) % SAMPLE_BUF_SIZE) == sample_buf_out;
+}
+
+void audio_fill(byte sample) {
+    sample_buf[sample_buf_in] = sample;
+    sample_buf_in = (sample_buf_in + 1) % SAMPLE_BUF_SIZE;
+    // enable interrupt
+}
+
+void audio_drain(void) {
+    if (sample_buf_in == sample_buf_out) {
+        // buffer is empty; disable interrupt
+    } else {
+        // buffer has a sample; output it
+        byte sample = sample_buf[sample_buf_out];
+        DAC_SetChannel2Data(DAC_Align_8b_R, sample);
+        sample_buf_out = (sample_buf_out + 1) % SAMPLE_BUF_SIZE;
+    }
+}
+
+// direct access to DAC
+py_obj_t pyb_audio_dac(py_obj_t val) {
+    DAC_SetChannel2Data(DAC_Align_8b_R, py_obj_get_int(val));
+    return py_const_none;
+}
+
+py_obj_t pyb_audio_is_full(void) {
+    if (audio_is_full()) {
+        return py_const_true;
+    } else {
+        return py_const_false;
+    }
+}
+
+py_obj_t pyb_audio_fill(py_obj_t val) {
+    audio_fill(py_obj_get_int(val));
+    return py_const_none;
+}
+
+void audio_init(void) {
+    // DAC peripheral clock
+    RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
+
+    // DAC channel 2 (DAC_OUT2 = PA.5) configuration
+    GPIO_InitTypeDef GPIO_InitStructure;
+    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
+    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
+    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
+    GPIO_Init(GPIOA, &GPIO_InitStructure);
+
+    // DAC channel2 Configuration
+    DAC_InitTypeDef DAC_InitStructure;
+    DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
+    DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
+    DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
+    DAC_Init(DAC_Channel_2, &DAC_InitStructure);
+
+    // Enable DAC Channel2
+    DAC_Cmd(DAC_Channel_2, ENABLE);
+
+    // from now on use DAC_SetChannel2Data to trigger a conversion
+
+    sample_buf_in = 0;
+    sample_buf_out = 0;
+    // enable interrupt
+
+    // Python interface
+    py_obj_t m = py_module_new();
+    rt_store_attr(m, qstr_from_str_static("dac"), rt_make_function_1(pyb_audio_dac));
+    rt_store_attr(m, qstr_from_str_static("is_full"), rt_make_function_0(pyb_audio_is_full));
+    rt_store_attr(m, qstr_from_str_static("fill"), rt_make_function_1(pyb_audio_fill));
+    rt_store_name(qstr_from_str_static("audio"), m);
+}